1. Field of the Invention
The present invention relates to mobile wireless devices as used in personal and asset location systems. In particular, the present invention relates to a method and apparatus for utilizing the Global Position System (GPS) to locate objects over a large geographic region and to provide information or services related to a real time position of the object.
2. Description of the Related Art
With the advent of the Global Positioning System (GPS), there is growing demand for mobile devices that can locate and track children, the elderly, emergency situations, tourists, security, valuable assets, and the like. Devices built using conventional GPS receivers have been developed by a number of companies. These current generation devices have major limitations in terms of indoor penetration, power consumption, accuracy, and acquisition time.
To address the above issues new GPS processing architectures have evolved that utilize a combination of mobile GPS receivers and fixed GPS infrastructure communicating via wireless links. Systems with this architecture collect the majority of the data for location using the fixed infrastructure and, compared to traditional GPS, are able to offer large improvements in accuracy, indoor penetration, acquisition time, and power consumption. Thus far, such systems are based upon a fixed site GPS receiver that is physically located in the local vicinity of the mobile receiver and are therefore difficult to extend to broad coverage areas without a large proliferation of fixed site GPS receivers. Furthermore, such systems require a wireless link that provides communication in real-time and therefore such systems cannot take advantage of non real-time messaging systems such as paging networks.
Thus there is a need for a GPS processing architecture and device technology that provides the benefits of improved accuracy, indoor penetration, acquisition time, and power consumption and also offers the capability to function over large geographic coverage areas without requiring a fixed site GPS receiver in the local vicinity of the mobile device. Furthermore, to take advantage of broad coverage messaging systems, the architecture should have the ability to operate over a link which is not real-time, i.e. a link where there is significant and possibly unknown message latency.